Photonics Dictionary: H

Also known as constant angle or constant deviation fringes. The interference fringes observed with dense flat plates near normal incidence. The fringes of the Fabry-Perot interferometer are Haidinger...

The total fusion and sealing of materials, or usually an enclosure, to ensure that they are airtight.

That part of the cladding wherein the refractive index is constant within a specified tolerance, as a function of radius.

A single housing that includes means of recording an image photographically and electronically.

A halogen lamp, also known as a tungsten halogen, quartz-halogen, or quartz iodine lamp, is an incandescent lamp that uses a tungsten filament surrounded by a small amount of halogen gas, such as...

1. In a cathode-ray tube, the glow surrounding a bright spot that appears on the fluorescent screen as the result of the screen's light being reflected by the front and rear surfaces of the tube's...

1. The value on either the leading or the trailing edge of a laser pulse at which the power is one-half of its maximum value. 2. The wavelength at which a filter is transmitting one-half of its peak...

In chemistry, a halide refers to a chemical compound containing one or more halogen atoms bonded to another element. The halogens are a group of elements in the periodic table that includes fluorine...

1. The faintly hued ring that is seen to surround a light source viewed through fog or light clouds. The size of scattering particles determines the size of the ring. 2. The ring surrounding a...

Any of the five elements astatine, chlorine, fluorine, bromine and iodine, grouped because their chemical properties are similar.

The process of sealing laser components by means of frit seals, welding or bonding rather than using epoxy.

A type of optical fiber in which a silica core is surrounded by a hard polymer or similar material much stronger than the customary cladding material.

Harmonic generation refers to a nonlinear optical process in which incoming photons interact with a material and produce new photons at integer multiples of the frequency of the incoming photons....

An optical system that superimposes a synthetic display providing navigational or weapon-aiming information on a pilot's or driver's field of view. The system includes a cathode-ray tube, collimating...

The process of subjecting glass to temperature cycling to produce physico-chemical reactions that alter its properties. Similar processes can be accomplished with a laser -- most commonly a CO2,...

A helium-neon (HeNe) laser is a type of gas laser that emits visible red light at a wavelength of 632.8 nm. It operates based on the principle of stimulated emission of photons from excited helium...

A photoanalytical instrument for analysis of jaundice conditions in infants that measures bilirubin (a breakdown product of hemoglobin that produces jaundice), albumen-carrying capacity and binding...

In optical communications, the translation of optical signals into radio signals, lowering their frequency in detection from greater than 1014 Hz to less than 1010 Hz, so that further signal...

High harmonic generation (HHG) refers to a nonlinear optical process in which intense laser light interacts with a gaseous medium, typically an atom or a molecule, to produce harmonics of the...

The holographic recording of sequences of high-speed phenomena. With a multiple beam laser, multiple holograms that depict rapid events can be formed on a single medium.

A high-speed motion camera, also known as a high-speed camera or slow-motion camera, is a specialized imaging device designed to capture fast-moving events or phenomena at extremely high frame rates....

A camera designed to record at rates exceeding 50 fps. For frame rates up to about 500 fps, an ordinary pull-down mechanism can be used. From 500 to 1000 fps, the film must be moved continuously, the...

Photography involving the recording of events that occur too fast to be perceived by the human eye or recorded by conventional photographic techniques. See high-speed movie camera; high-speed...

Histochemical staining is a laboratory technique used in biology and medicine to visualize specific chemical components within biological tissues. This technique involves the application of various...

Histology is the branch of biology and medicine that involves the study of the microscopic structure of tissues and organs at the cellular and subcellular levels. It is a field that focuses on the...

An infrared-transmitting optical fiber with a hollow core; it can be square, round or rectangular in cross section. Capable of carrying high laser power but subject to high bending losses.

Holmium lasers are a type of medical laser that utilizes holmium-doped crystals as the gain medium. The term holmium laser is often associated with a specific type of laser used in urology for...

A holographic camera, also known as a holographic imaging system or holographic recorder, is a specialized device used to capture 3D holographic images of objects or scenes. Unlike conventional...

A technique used to create a series of interrelated holographic images that give an appearance of motion when projected in sequence. A flashing laser is used in both the recording and projecting of...

A holographic grating is a type of diffraction grating that is produced using holographic recording techniques. It consists of a periodic structure of alternating transparent and opaque regions,...

The interferometric analysis of a complex object by utilizing the three-dimensional hologram. By causing a laser beam to diverge into two directions, one of which directly strikes a holographic...

A photographic recording of interference patterns between a plane wave and a spherical wave on a high-resolution photographic emulsion.

The holographic recording of a microscopic specimen whereby magnification is achieved by alteration in a wavelength or radius of curvature between recording and reconstruction of the wavefront. With...

A component used to modify light rays by diffraction; the HOE is produced by recording the interference pattern of two laser beams and can be used in place of lenses or prisms where diffraction...

A method of measuring flow velocity by seeding the flow with neutrally buoyant particles and using a pulsed laser to holographically record particle displacement during a short time period. An...

Holographic tomography is an advanced imaging technique that combines holography and tomography to provide three-dimensional reconstructions of transparent or weakly scattering objects with high...

Holography is a technique used to capture and reconstruct three-dimensional images using the principles of interference and diffraction of light. Unlike conventional photography, which records only...

A series of permanent holograms in dichromated gelatin formed by opening total page-composer apertures and setting a point source of light in each storage location. It performs much like a...

A device where each pixel in the detector array is mated with a preamplifier on a single silicon chip, providing sensing and signal processing capabilities.

A hydrogel is a three-dimensional network of polymer chains that are hydrophilic, meaning they have a strong affinity for water. This network structure allows hydrogels to absorb and retain large...

Hydrophilic is a term used to describe substances or materials that have an affinity for water. The word hydrophilic comes from the Greek words "hydro," meaning water, and "philos," meaning loving or...

Hydrophobic is a term used to describe substances or materials that repel or do not readily interact with water. The word hydrophobic comes from the Greek words "hydro," meaning water, and "phobos,"...

Hyperchromic shift refers to an increase in the absorption of light, leading to a higher absorbance, often observed in certain chemical or biological substances upon undergoing a structural change....

Hyperspectral imaging is an advanced imaging technique that captures and processes information from across the electromagnetic spectrum. Unlike traditional imaging systems that record only a few...

A hyperspectral imaging camera is a sophisticated imaging device capable of capturing and processing data across a wide range of wavelengths within the electromagnetic spectrum, typically from...

Hyperspectral resolution refers to the level of detail or granularity in the spectral information captured by a hyperspectral imaging system. In hyperspectral imaging, the electromagnetic spectrum is...

This term literally means "to lag behind.'' It is quite often used to describe the residual effect that remains after the primary effect has been removed, or the lag that exists between the...